1. Field of the Invention
The present invention relates to a buckle device equipped with a switch that detects the state of attachment of the tongue plate, which is provided at the seat belt, to the buckle body.
2. Related Technology
Seat belt devices for protecting occupants during an accident such as collision have been mounted on seats of various transportation mechanisms such as automobiles. The seat belt device of such kind is provided with a buckle device for attaching and detaching the seat belt in an easy manner.
The buckle device of this kind is constituted by a tongue plate having the seat belt (waving belt) passed therethrough and a buckle body serving to engage and disengage the tongue plate. A latch member that locks the tongue plate, a base member that movably supports the latch member, an ejector that slides following the insertion or removal of the tongue plate and moves the latch member by such sliding movement, and a switch that detects the state of engagement of the tongue plate with the buckle body are typically provided inside an outer case of the buckle body.
Patent Document 1, Japanese Patent Application Publication No. 2005-190906, and Patent Document 2, Japanese Patent Application Publication No. 2001-224407, disclose buckle devices that use as the aforementioned switch a slide switch having a fixed contact and a movable contact that switches the switch state by sliding with respect to the fixed contact.
In the buckle devices described in these patent documents, a slide switch is constituted by mounting a base plate or a switch case provided with a fixed contact inside an outer case and mounting a movable contact on a slider provided so as to slide with respect to the base plate or switch case. The switch is set so that when the tongue plate is locked to the buckle body, the slider moves and assumes the ON state, and when locking of the tongue plate is released, the slider returns to the original position and assumes the OFF state.
However, in the conventional buckle device, the fixed contact is mounted on a member such as the base plate or switch case, and this member is then mounted on the outer case or base frame. Therefore, it is possible that the fixed contact will move and the position detection will not be performed reliably.